hi--this morning we observed a lot of sidewalk ants swarming in our backyard (coming in/out of pavement cracks). there were winged ants (males?) flying up and dropping down periodically. some seemed to be struggling--flying around on their backs before righting themselves. now this evening there is no swarm, but some new piles of debris along some of the pavement cracks that a few ants are tending.
what was going on this morning? any help is appreciated!
Although it is hard to identify the ants without pictures, it is quite possible that they are the common European pavement ant (Tetramorium caespitum), which have become one of the most abundant insects in the Northeastern US. If you want to try to identify them, follow this link to the AntWeb species page for Tetramorium caespitum.
As the winged ants are the reproductive members of the colony, it is possible that the colony you are observing was sending out queens and/or males to reproduce with other nearby colonies. Often, they form mating swarms with queens and males from many different colonies, so if the all the members of the swarm were winged, then it is likely that you were observing a mating swarm.
If there were only a few winged members in the swarm, then it is possible that you were observing a territorial battle between two different colonies of Tetramorium caespitum. These are fairly common on sidewalks and between pavement cracks, and have been documented well by the fantastic photographer Alex Wild. See the picture below for an example of these battles (Photo by Alex Wild).
I hope this answers your questions!
Max Winston & the AskAntTeam